We have a garage built enclosed double stack small enough to be pulled behind a mini-van, upper floor is of plywood with tie downs in the frame and floor. Back end is like a regular enclosed trailer that you normally see. Then we have an angular nose in the front, to help the aerodynamics and with its own hatch for hauling tool boxes and such. Everything is lockable. The other thing done with it is has 17-inch rims so it pulls fairly easy.
Bug - Alley Kat II - McCulloch - Coyote - B&S LO206